Pcm Code P044 - Rear Oxygen Sensor Lean Signal: Action

PCM turns on SERVICE ENGINE SOON light. PCM turns on canister purge solenoid if Code P042 is also set.

NOTE: Test numbers refer to numbers on diagnostic chart.

If PCM Code P013 is present, diagnose this code first since an oxygen sensor not ready can cause other emission related problems.
If oxygen sensor is operating correctly, voltage should fluctuate at greater than 0.3 volt. A lean sensor condition will cause voltage to remain at less than 0.3 volt.
If voltage measured is greater than 0.15 volt, PCM and circuit No. 412 are okay. See CHART 7 under POWERTRAIN CHARTS.

Fig 1: PCM Code P044 Schematic - Rear O2 Sensor Lean Signal

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P044 Flow Chart - Rear O2 Sensor Lean Signal

Courtesy of GENERAL MOTORS CORP.